Effect of Urtica dioica Leaf Alcoholic and Aqueous Extracts on the Number and the Diameter of the Islets in Diabetic Rats.

Urtica dioica has been known as a plant that decreases blood glucose. Despite the importance of this plant in herbal medicine, relatively little research has been down on effects of this plant on islets yet. The objective of the current study was to evaluate the effect of dried Urtica dioica leaf alcoholic and aqueous extracts on the number and the diameter of the islets and histological parameters in streptozocin-induced diabetic rats. Six rats were used in each group. Group I: Normal rats were administered saline daily for 8 weeks. Group II: Diabetic rats were administered streptozotocin, 50 mg/kg of body weight; Group III: Diabetic rats were administered dried Urtica dioica leaf aqueous extracts for 8 weeks; Group IV: Diabetic rats were administered dried Urtica dioica leaf alcoholic extracts for 8 weeks. The animals, groups of diabetic and normal, were sacrificed by ether anaesthesia. Whole pancreas was dissected. The tissue samples were formalin fixed and paraffin embedded for microscopic examination. Histologic examination and grading were carried out on hematoxylin-eosin stained sections. The effects of administration of dried Urtica dioica leaf alcoholic and aqueous extracts to diabetic rats were determined by histopathologic examination. The pancreas from control rats showed normal pancreatic islets histoarchitecture. Our results also, indicate that the pancreas from diabetic rats show injury of pancreas tissue while the pancreas from diabetic rats treated with dried Urtica dioica leaf alcoholic and aqueous extracts show slight to moderate rearrangement of islets. According to our findings, dried Urtica dioica leaf alcoholic and aqueous extracts can cause a suitable repair of pancreatic tissue in streptozocin-induced diabetic experimental model.

in the treatment of diabetic diseases (6). UD is also known for its use against diabetes in folk medicine (7)(8)(9). As reported by many other investigators U.
dioica is a plant belonging to the plant family Urticaceae. The blood sugar lowering effect of U. dioica as a medicinal plant has been reported (10).
U. dioica leaves extract given parenterally possesses a hypoglycemic effect in alloxan hyperglycemic rats (11). Urtica dioica extract had hypoglycemic and antidiabetic activities (12). The extract of UD was unable to enhance the glucose utilization directly (13).
In view of the above mentioned varied unique pharmaceutical and biological application of dried Urtica dioica leaf extracts, it may be pragmatic to say that this plant have the potential to be used as active compound in diabetes. The objective of the current study was to evaluate the effect of dried Urtica dioica leaf alcoholic and aqueous extracts on the number and the diameter of the islets and histological parameters in streptozocin-induced diabetic rats.

Preparation of Urtica dioica leaves
Urtica dioica leaves were purchased from herbalists in Babol, Iran. The leaves were separated and dried at room temperature while keeping away from direct sunlight and then were grounded into powder.

Preparation of the aqueous and alcoholic powder of Urtica dioica leaf extracts
In order to prepare the aqueous concentrate,

Diabetic induction
Diabetes was induced by intraperitoneal injection (50 mg/kg, i.p) of 0.6 ml of freshly prepared solution of streptozotocin (STZ) dissolved in distilled cold normal saline. Rats were not fed 14 hrs before injection. In addition, 0.7 ml normal saline was injected to rats in the control groups.
Rats with fasting glycemia more than 250 mg/dl were used as diabetic. Blood samples for glucose measurements were taken from the tail vein.
Diabetes was confirmed by measuring the glucose concentration.

Animals administration
Animals were randomly divided into four

Statistical analysis
All values have been presented as mean ± standard error. All tests were carried out in triplicate. Statistical analysis were done using SPSS version 16.0. The significance of differences between the mean values were determined by analysis of variance (ANOVA) or was determined using an unpaired two-tailed Student's t-test, and a p value of less than 0.05 was considered statistically significant.

Effect of dried Urtica dioica leaf alcoholic
and aqueous extracts on number of islets and islets diameter in normal and diabetic rats was shown in Table 1. Our results indicate that administration of streptozotocin intraperitoneally reduce the cellularity and diameter of islets compared to the control group. Administration of dried Urtica dioica leaf ethanolic extracts significantly increased the cellularity and diameter of islets in treated group compared to diabetic group. Also, the diameter and cellularity of islets in rats treated with Urtica dioica leaf aqueous extracts significantly increased. There were no abnormalities in the pancreas of normal rats (Fig.1). Diabetic rats showed injury of pancreas tissue (Fig.2). The Diabetic rats treated with ethanolic Urtica dioica leaf extracts showed moderate repair of pancreatic tissue (Fig.3).
Diabetic rats treated with aqueous Urtica dioica leaf extracts also showed slight to moderate repair of pancreatic tissue, probably due to partial regeneration of the pancreatic cells (Fig.4).

Discussion
Histopathological aspects of pancreatic